Extracting method and apparatus



Dec. s, 1936.

J. J. DE LA RozA. sR

EXTRACTING METHOD AND APPARATUS s sheets-sheet 2 Filed Oct. V24,` 1934 I INVENroR. Joaquin Ju/odebnzan BY 5,

ATTO EYS.

Dec- 8, 1936- J. J. DE LA RozA, sR 2,063,367

EXTRACTING METHOD AND APPARATUS Filed Oct. 24, 1934 5 Sheets-.Sheet 3 .III IIll-llllllhl` ATTO NEYS.

Patented Dec. 8,. 1936 UNITE-D STATES PATENT oFFlcE EXTRACTING METHOD AND 'APPARATUS Application October 24, 1934, Serial No. 749,741

12 Claims.

My invention relates to an extracting method and apparatus and more particularly to a method and apparatus for removing uid from vegetable or cellulosic material.

In the manufacture of paper pulp from cellulose bearing materials the recovery of certain of the chemical constituents of the digesting liquor is desirable in order that the cost of manufacture may be kept Within an economical figure.

10 The pulp on being discharged from a digester is ordinarily subjected to a series of operations for the extraction of the digesting liquor wherein the pulp is thoroughly washed before being delivered to subsequentoperations incident `to the manu- 5 facture of cellulose and paper. For example, in

the alkaline processes, in the first washing operation it is customary to dilute one to three parts of pulp with ninety seven to ninety nine parts of water or black liquor in a washer from which the pulp is delivered to a repulper and thence to a second washer. In this second washer the dilution will again be in the ratio of one to three parts of pulpV to ninety seven to ninety nine parts of Water. It is obvious that with a series of operations of this type much of the chemical is lost in the Wash waters since it is not economically feasible to evaporate the large amount of water necessary for the recovery of the chemical content in such dilute Wash liquors.

It is an object of my invention to provide a process for extracting fluids from pulp, fibrous or fluid containing materials which will effect an optimum recovery of the chemical constituents, and the heat content of the fluid at a high temperature.

It is a further object of this invention to provide a process forV removing from pulp, or other treated material, at elevated temperatures and pressures the incrustants and coloring matters which are soluble or suspended as colloids in the treating liquor` at the high treatment temperatures and pressures.

It is a further object of this invention to provide a novel combination of apparatus capable of removing from a digesting vessel a measured :quantity of pulp in its homogeneous ratio f 1iq.

ing sleeve functioning as a metering device and shut-01T valve between a digester and the pressing' zone.

Another object of my invention is to provide a novel means for controlling the density of the 5 material being pressed.

It is a further object of this invention to provide a novel straining or filtering device for high pressure separation of liquids from liquid containing material without objectionable clogging of the strainer ports.

Another object of my invention is to provide a pressing process and apparatus which may be employed generally for the following purposes:

1. The extraction of sugar juices from sugar cane. In this process a battery of several presses `will be used, with or without maceration water, depending on outside factors.

2. The extraction of cotton seed oil from cotton seed, with or without the use of a-solvent, depending on outside factors.

' 3.'The extraction of .castor oil from castor beans, or other oils from any other beans, such as soya beans, etc., usuallycarried out without a solvent and either hot or cold depending on 25.

Whether the oil is for use for mechanical or medicinal purposes.

4. The extraction of fats from garbage and similar sources of waste. This is usually carried outfhot, with or without the use of a solvent.

5. The extraction ofA juices from cachaza. (Cachaza is the sediment obtained in the clariiication of juices in the manufacture of sugar.)

6. 'I'he extraction of juices from grapes and the like with or without the use of a solvent, such as w'ater, for the manufacture of liquors.

7. For the chemical treatment of various substances in which the treatment is followed by a pressing operation to remove as much of the chemical as possible as in nitrating, mercerizing, 40 etc. For instance: The' manufacture of rayon by the viscose process wherein cellulose lpulp vis soaked with concentrated caustic soda for a short period of time and then the excess alkali solution is removed from the lalkali cellulose by pressing in so-called filter presses. In this connection I wish to call attention to the fact that what I have in'mind is a combination of the viscose process and a pulp producing process such as is covered in some of my'patents for50 Yproducing cellulose. In such anarrangement, raw vegetable material would be introduced into a battery of presses and high grade viscose alkali cellulose suitable for rayon manufacture would @merge from the last part of the equipment, re-

sulting in a very simple and economical process and apparatus for manufacturing rayon and pregnating the material with liquors, gases, rvapors or finely divided solids by pressing in one or more stages. The impregnation as carried out allows the loosely packed material to absorb an amount of the added substance, the subsequent very high pressure pressing serving to displace undesired substances contained in the material, such as air, oxygen; liquids or gases, with the added substance. This may be done hot vor cold and under various pressures from low vacuum to very high pressures as the case may be, in an open or closed system.

Other and further objects of my invention will appear from the following description.

In the accompanying drawings which form part of the instant specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views;

Figure 1 is a side elevation of the .outlet end of. a digester equipped with one form of apparatus embodying and capable of carrying out my invention.

"Figure 2 vis an enlarged view of a detail shown partly in section of thev apparatus in Figure l.

Figure 3 is a plan view vof the sleeve valve and pressing plunger mechanism shown in Figure 1.

Figure 4 is a side elevation of the assembly shown in Figure 3, showing the sleeve valve and plunger in one position:

Figure 5 is a view similar to Figure 4, showing the sleeve valve and plunger in another position.

Figure 6 is an enlarged sectional view of the sleeve valve and plunger mechanism shown in Figure 4.

Figure "l is an end viewof the detail shown in Figure 6.

Figure 8 is an end view of the novel filter assembly.

line 9-9 of Figure 8.

Figure 10 is a sectional view taken along the line Ill- I0 of Figure 9.

.Figure 11 is a fragmentary sectional viewv on an enlarged scale of the filter assembly with a numafter particularly with relation to the-extraction of black liquor from pulp produced as the result of the acid or alkaline cooking of cellulose bearing materials under heat and pressure.

In general, 'thesemi-liquid mass of digested pulp and black liquor delivered from the digester is introduced into a pressing device. Such a dek'lo vice may be, for example, a piston operating within a perforated or slotted and jacketed cylinder. I prefer, however, to"use1:'th e apparatus herein shown. The friction of the cylinder walls, which may bel augmented by formingthem of progressively decreasing diameteri-and-the pressing acnon ofthe piston ,causes information of a dense Figure 9 is a sectional view taken along the tion of movement.

plug from whichthe chemical liquor flows and is carried away through suitable perforations or slots of the cylinder. The exit end of the cyl- 'inder may be provided with a valve which is closed at the start of the pressing operation in order to promote the building up of the plug to a density necessary to permit the desired extraction of liquor. I prefer, however, to use Ithe automatic valve means herein shown. The plug, as formed, is intermittently moved forward through `the cylinder and discharges into any suitable form of shredding or `repulplng machine capable of breaking up the plug into many sub-divisions. A diluting liquid which may be, -for example, water, or weak black liquor, or a bleaching or other chemical treating uid generally substantially at the temperature of the liquor in the material fed to the'iirst press is added to the material in such quantity as to restore it to approximately its original fluid consistency and it is then introduced into the chamber of a second cylinder vand piston pressing device. This second press may be substantially identical with the first and the operation is again repeated to extract a major portion of the diluted chemical liquor from the pulp which may be again shredded or repulped and delivered to a washer for nal separation of the very dilute chemical liquor from the pulp. leaving this last washer maybe diverted in certain cases in whole or in part to the diluting stage placed before the second press. The chem- "ical liquor from the first' press and the diluted chemical liquor from the second press may be combined and/or separately delivered through heat exchangers for the recovery of the heat content and then passed to the usual recovery apparatus for the separationvand recovery of the chemical constituents or other valuable substances contained therein. x

' More particularly referring now to the drawings, the digested pulp and black'liquor from digesting zone l passes therefrom through stop valve 2. This stop valve may be of any suitable type. I prefer, however, to use a non-clogging stop valve of my invention, which forms `part of my co-pending application, Serial No. r148,008,

The wash water filed October 12, 1934. The stop valve may lbe operated either by hand through hand wheel 3 or by an electrically driven motor 4. The senilliquid mass of digested pulp and black liquor passing through the stop valve 2 passes through duct 5 to the pressing device shown more fully in'Figures 3 to 13 inclusive. The pressing device is essentially an elongated strainer into which the digested pulp is rammed by a reciprocating plunger. The chemical liquor is withdrawn through suitable outlet ducts |99 in strainer sections 6 and l and the plug of pulp becomes propressively denser. This is due to the fact that the sections 9, 9, I0, and Il form a .convergingpassageway, being internally tapered in the direc- Inasmuch, however, as the density is dependent upon the friction of the vsection walls, the taper merely provides a means for reducing the overall length of the friction passage. In order to insure that the chemical liquor is being extracted to the desired extent and that the paper pulp is -not simply being I4, which is actuated by a uid pressure piston I5, working in cylinder I6. The fluid pressure may be either compressed air, steam, hot air or the like. The piston rod I1 of the piston I5 is secured to the piston I4 in any suitable manner.

'Piston |4 is really a valve and is adapted to seat against the periphery I8 of section IIJ. Any seat may be used but I prefer the non-,ologging valve seat shown in my co-pending application, Serial No. 748,008, led October 12, 1934.

Section II houses' a tubular section I2, which is provided with a passageway of progressively decreasing diameter in the direction of movement of the pulp or material being processed. Section |I is provided at its upper end with a shaft I9, mounted as can best be seen in Figure 15, and passing through a suitable stuffing box 20 into the interior of section II above the sleeve or tubular member I2. Keyed to the outer end of shaft I9 is a lever 2|, while keyed to shaft I9 within section II, is a lever 22, carrying a projection 23,which is adapted to enter a circumferential groove 24 formed in sleeve I2. The sleeve I2 is mounted for movement within section II upon bearing sleeve 24 and within bearing sleevev 25 as can readily be seen by reference to Figure 14. The bearing surfaces, namely, the-outer surface of sleeve 24 and the inner surface of sleeve 25 are packed by chevron rings or other suitable packing, as clearly shown in Figure 14. The lever 2| is biased by spring 26, tending to move the lever 2| to the right as viewed inFigure 14, thus tending to rotate shaft -I9 clockwise. It will be obvious that movement of shaft I9 in a clockwise direction will carry lever 22 to the left as viewed in Figure I4 and likewise move sleeve I2 to the v left. It will also be obvious from the construction within groove 24, movement of sleeve I2 to the right will move lever 22 to the right, tending to rotate the shaft I9 counter clockwise against the action of spring 26. Spring 26 thrusts at one end against adjusting screw 21 which may be moved to vary the compression upon spring 26 within certain limits. If the resistance upon sleeve I2 is insufficient to overcome the action of the spring, it will be obvious that the spring will bias the lever 2| to the position shown in Figure 14. Lever 2| is mounted between circuit makers 29 and 52, as can readily be seen by reference to Figure 2. If the frictional resistance of the ma.

terial passing through sleeve I2 is great enough to overcome the action of spring 26, the sleeve I2 will be moved to the right, thus moving lever 2| Ato the left to the position shown in Figure 2.

In this position, the lever vwll throw circuit marker 9 to the position shown in Figure 2,-

bridging contacts 30 and 3|, completing the circuit which will now be described. Conductors 32 and 33 are connected to asuitable source of potential. Current will ow through conductor 33, through conductor 34 to contact 3| through circuit maker 29, to contact 3| through conductor 35, which leads to solenoid or electromagnet 36, through the winding 31 of the solenoid or electromagnet 36, through conductor 38 to the negative side of the line, through conductor 32. In this position, armature 39 will be drawn downwardly by solenoid 36. Attached Vto armature 39 is a valve stem 40 passing through a suitable stu'ng box 4I into cylinder 42 and having secured to its end a. piston valve 43. A uid pressure medium, such as steam for example, is supplied through pipe 44 to the cylinder 42, entering it through port 46. With the valve in position as shown in Figure 2, port 45 is placed in communication with port 46 allowing the steam to pass through pipe 41 which leads to the cylinder |6vopening thereinto on the under side of piston I5. The steam will force the piston to the position shown in Figure 2 exhausting the steam which might be above piston I5, through line 48 which opens into cylinder 42,'through port 49 above the valve 43. Port 49 is in communication with port 50, to which pipe 5| is connected. Pipe 5i is connected to any suitable exhaust such as the atmosphere.

Assuming that the plug of digested material is of insuflcient density as it would be if the chemical liquor were not extracted therefrom to a suitable extent, as would be the case if the digested material were allowed to pass through the strainer to the converging passageway without suicient resistance, the spring 26 would then act upon lever 2| to rotate shaft I9, moving sleeve I2 to the left through lever 22. In this movement,

the lever 2| would be carried to the right, moving it against circuit maker 52, closing the circuit across contacts 53 and 54. When this occurs, the circuit across contacts 30 and 3| will be broken and current will flow through conductor 33, through conductor 55, to contact 53'across circuit maker 52, to contact 54, throughv conductor 56, to the solenoid 51, through the winding 58 of the solenoid, through conductor 59, to conductor 32, to the negative side of the line, thus energizing solenoid 51. This attracts the armature 39 upwardly, moving valve 43 upwardly to a position in which port 46 is placed in communication with port 60 and port 45 is placed in communication with port 49. Steam entering through port 45 now flows through port 49 and line 48 to cylinder I6, entering it above piston I5, forcing it and hence piston valve I4 downwardly, seating the valve I4 against seat I8 and closing off the flow of digested material. The lsteam which was below piston I5 now passes out through line 41 and enters cylinder 42 below valve 43 which is now in raised position. The exhaust steam passes through port 6I) and line 6|,

ythrough which it passes to exhaust.

After the digested material has been compressed to a suitable extent, its density becomes greater and its frictional resistance becomes large enough to move sleeve I2 to the right, thus moving lever 2| to the left against the action of vspring 26, again actuating circuit maker 29 to added to the compressed. pulp to dissolve any.

projections 68 and 69. This repulps, or shreds, the pulp and the re-shredded pulp passes through connection 10 to a Asecond duct 5, leading to a second press and filter similar in all respects 7o` are adapted to pass closely adjacent to fixed to the rst press and filter described, where the action is again repeated. If desired, the pressing,l

diluting, and re-pressing may be repeated as often-as is necessary to recover the chemical. The value of the chemical to be recovered, the extent of chemical' treatment to be given, and the amount of chemical present at the end of a givenpressing stage will govern whether it is economical to continue the process further.v

Referring now to the details of thepressing mechanism and its associated parts, a steam engine 1| drives a disk 12 through a suitable gear train 13, 14, the disk 12 being provided with a gear tooth periphery 15. Connecting rod 16 is secured to the disk by a crank 11. A plate 18 is rmly secured to the disk by a crank 11. A plate 18 is firmly secured to the disk 12 in any suitable ma'nner and is provided with a cam track 19. A pair of tooth disks 12 are shown in Figure 3 in order to equalize the torque. The disks 12 turn upon journals 13' in suitable bearings 14 which are liousedupon a pedestal 80 of any suitable design. The pedestal 80 is provided with a slot 8| adjacent which is mounted a bell crank lever 82 which is pivoted on a suitable fulcrum 83. l

One end of the bell crank lever 82 carries a cam follower 84 which rides in cam track 19.

' The other en'd of bell crank lever 82 is connected lso -mby link 85 to one end of a lever 86`which is fulcrumed to the pedestal at 81. To the other end of lever 88-is pivoted at 88 a connecting rod. 89.

`The other end of the connecting rod is pivoted to sleeve valve 90. 'I'he connecting rod 16 is secured to forkA 9| by wrist pin 92. lRani or plunger 93 is rmly secured to fork 9|. 'I'he plunger 93 is adapted to work ,within sleeve valve 90 which passes into casting 5 through suitable stuiling box 94 which is provided with chevron rings 95 which are pressed sealingly'against sleeve valve v90l by means of stuillng box follower 96 and nutsV 91 acting upon stud bolts 98 as can readily be seen'by reference to Figure 6. The outward end of sleeve valve 90 is internally bored at 99 forming an annular skirt of reduced thickness. An annular valve seat |0| is spacedly supported from the internal walls of passageway |02 by spacing members |04 which may be integral with the valve seat |0|, forming an annular passageway |03. The exterior surface of valve'seat |0I may be formed along the surface of a cone presenting a tapered portion |05 which forms a con-` verging passageway as can readily be seen by reference to Figure 6. The dimension of the .passageway |03'is such that it just, accommodates the annular skirt |00. The internal diameter of the opening |08 of the valve seat |0| is such that it will accommodate the plunger 93.y The casting or forging 5 is provided with a Aange |01 and is adapted to be connected with flange |08 of the illteror strainer member |09 which will be hereinafter more fully described.

In operation, pulp enters the passageway ||0 of casting 0, the sleeve valve 90 and the plunger 93 being withdrawn to the position shown in Figures 4 and 6. Asthe disk 12 rotates in the direction shown by the arrow in Figure 4, the sleeve valve 90 and the plunger'start moving to the right as viewed in the drawings. The cam track is such that the'follower 84 will move up wardly, moving the lower end of .the bell crank lever 82 to'the left, moving link 85 to the left, moving the lower end of lever 86 to the left and thrusting the upper end of the lever 88 to the right. moving the sleeve valve 90 across the openingv ||0, blocking the ow of pulp through passageway I0. The motion of the sleeve valve 90 is Figure 4, the connecting rod 16 which actuates the plunger 93 is at, dead center. vBy the time disk 12 has moved through an angle of about' 45 degrees, the sleeve valve 90 will have completely vclosed the passageway ||0. Pulp will be jammed by skirt |00 into the passageway |03 which. due to the converging shape thereof, will jam a ring of pulp between the walls |02 and the tapered sides '|05 of the valve seat |0|. This forms a sealing ring which prevents leakage. With each fresh action of the valve 90, the old ring of pulp will be forced through the passageway |03 so that the valve is tight and non-clogging.

In the position shown in Figure 5, the sleeve valve 90 is shown in .its seated position. The plunger 93 is moving to the right at its greatest velocity, being in the mid position of its stroke. It will continue tov move to the right forcing the pulp intoI the lter Aor strainer |09, pressing the chemical liquor from the pulp lin a manner which 'will be hereinafter more fully described. As the disk 12 continues to rotate, the plunger'93 will move to the left, completing its reciprocating movement and the sleeve valve will finally open, allowing a fresh charge of pulp to enter. The lter comprises a cylindrical member 09 to which are secured flanges |08 and Longitudinally extending stringers orbearing members 2 are welded or otherwise suitably Asecured to the* internal surface of cylinder |09 as can readily be seen byl reference to Figures l1 and l2. The stringers l2 are suitably spaced completely around the internal surface of cylinder |09. The ends of stringers ||2 are tapped at ||3. Assembled within the cylinder 09 and supported by the bearing stringers ||2 are a.' nest of rings spaced from each other a predetermined distance. The annular space formed between adjacent rings is the restricted area which forms the passageway for the liquid being pressed. 'I'his passageway is small enough to retain the solid material, while permitting the liquid to pass through. Secured algainst the ends of bearing stringers ||2 by screws |I4, which are adapted to screw in tap holes ||3 are holding rings ||5^and H8, adapted to hold the assembly of filtering rings in place longitudinally. Flange is provided with a peripheral recess. Flange is adapted to be bolted to ange ||1, .which is likewise provided with a peripheral recess.' Holding ring Y| I5 is of larger diameter than the cylinder |09 and is adapted to seat in the space formed by the pe- .riperal recess in flanges and ||1 and will be` clamped therebetween by flange bolts I8. A suitable gasket I9 may be provided. It will be observed, as can be readily seen by reference to Figures 9 and 11 that the filtering rings |20 are identical. One surface |2| of the ring is in a plane perpendicular to the axis of the ring. The

other surface |22 of the ring lies along the surface of a cone whose base is in the plane of the surface |2|. Spacedly positioned around the vinclined surface |22of each ring are va plurality of accurately drilled holes |23 into which are adapted to ilt with apush fit, stub steel pins |24. In one embodiment of my invention, the rings had an external .diameter of' `'1.7500 inches. A tolerance of .00125 inch was permitted. The internal diameter of the rings |20 was 6.0600 inches. 75

`a similar tolerance of .00125 being permitted.

The thickness of the rings was .'745 inch at the internal surface. 'Ihe rings were finished to a ground finish with a tolerance of .0005 inch. At the external surface or the outer periphery of the ring, the thickness was 1% of an inch. The shoulder |25 of the rings was 1/64 of an inch wide. The diameter of the drill holes was 1% of an inch. 'I'he holes were drilled exactly to b/s of an inch from the plane surface |2|. The length of the pins was 41/64 of an inch exactly. In assembling, the pins were pushed intoplace and their outer surfaces ground so that the space between the plane of the outer ends of the pins and the plane |25 was less than .005 inch with a tolerance of .0005 inch. Each cylinder |09 was of such length that forty-six rings were used. It. will be seen that the capillary opening between one surface |25 of a ring and the adjacent surface |2| of the adjacent ring in the embodiment just described was less than .O05l of an inch. It will, be readily apparent that this opening can be varied by the use of pins of differing lengths. The opening may be thus made larger or smaller depending upon the type of material being pressed.y

At a suitable place in the cylinder |09 I provide an inspection opening which is normally closed by a plug |26 seating upon va ring |21 which is welded to the cylinder. Bolts |28 secure the plug |26 to its seat which may be provided with a` be used instead of supporting stringers and the straining surface may be made by micrometrically spaced strainers having their sides tapered similar to the rings. t

In operation, the pulp being pressed will give up its chemical liquor which will ow through the filtering slots between adjacent rings and out of the drains |30. The rings are of sufficient strength and are suiciently well supported to form a compact assembly capable of withstanding the pressure. The rings and the pins and associated parts may be made out of metal which will be non-corrosive or resistant tothe chemical action of the particular type of liquor being used. In the conventional washing operation, using a Washer of the prior art, black liquor is removed in an amount which will produce a mass of material containing a maximum of about 25 to 30' pounds of pulp to 70 to 75 pounds of liquor. This may be spoken of as a mass whose density of pulp is a maximum of 25 to 30 percent. In the operation of my process and using the apparatus of my invention, the pressing is sufficiently high to produce pulp of 55 to 60 percent density, that is 55 to 60 pounds of bone dry pulp to 40 to 45 pounds of black liquor.

An example of the operation of my process is as follows:

T0120 pounds of wood chips, containing 20,

pounds of moisture, I used 280`pounds of white liquor for digesting purposes. The white liquor contained the cooking chemicals; for example, 25 pounds of sodium hydroxide. Assuming that there is little or no loss of material in the form vsequent washing operation.

of vapors or gases, 400 pounds of pulp stock will be removed from the digester at the completion of the digesting operation. If a 40 percent yield of pulp is achieved by the digesting operation, 40 pounds of dry pulp and 360 pounds of black liquor will result. This pulp had a density of 11+ percent. The 360 pounds of black liquor contained approximately 25 pounds of sodium hydroxide. The first pressing operation produced pulp having a density of 50 percent, that is, there were 40 pounds of pulp to 40 pounds of black liquor. The 320 pounds of black liquor extracted contained 22.2 pounds of sodium hydroxide with a minimum of dilution, leaving 2.8

pounds of sodium hydroxide in the 40 pounds of this and eects an economical recovery by shredding or re-pulping the pressed pulp from the rst pressing operation, to which pulp has been added weak black liquor recovered from a sub- The weak black liquor is added only in sufficient quantity to re- -store substantially the original low density. As-

suming that 320 pounds of weak black liquor containing some sodium hydroxide (depending upon the wash water. used) is added to the shredded pulp, which is again' pressed to a1' density of 50 per cent. This pulp will then have 40 pounds of bone dry pulp and 40 pounds of the diluted black liquor. This black liquor will retain only .31 pound of sodium hydroxide. The dilute liquor removed from the second pressing operation will contain the remaining 2.47 pounds of sodium hydroxide, with a minimum of dilution. Then, too, the .31 pound of sodium hydroxide remaining in the black liquor contained in the pulp after the second pressing operation is partially saved by using the wash water from washing this pulp to dilute the pulp resulting from the first pressing operation. The pulp delivered from the second pressing operation is shredded or re-pulped and then delivered directly to the washing apparatus from which the dilute black liquor is returned to the second pressing operation, as pointed out above.

It will be seen that there are three main econ- 'omies eiected by pressing the pulp to a very high density to extract the chemical containing liquid before the pulp is allowed to cool or expand, namely,

1. By pressing the liquor from the pulp while itis substantially at the same pressure and temperature as the digester contents and then passing this liquor through heat exchangers, the heat from the liquor can be recovered atl a temperature and pressure substantially equivalent to the digesting temperature and pressure thus 7effecting a thermally efficient recovery of heat. The result is that there is produced a quantity of high temperature steam instead of a large and useless quantity of hot Water as is veffected by ordinary batch digester heat recovery operations. I

2. The pressing of the liquor from thel pulp while it is approximately at the same pressure 6\ liquor pressed from the pulp. If the removal of "this black liquory is accomplished by a temperature below the digesting temperature, a large proportion of these coloring matters and other substances become insoluble as the liquor cools and becomes saturated, thus precipitating coloring matters within the pulp, making it necessary to spend additional effort and chemicals to remove them. i

3. The use of a system of powerful reciprocating presses forremoving the black liquor of minimum dilution enables the recovery of the dissolved chemicals in highly concentrated form and is particularly economical since it reduces the amount of water to be evaporated later on in the recovery process.

It will be obvious that my method and appa- Aratus can be employed for the extraction of one substance from another by pressure, with or without previous or subsequent digestion as in the vegetable oil extracting art, in the art of extracting juices from fruits, vegetables, sugar cane and the like, etc.

It will be understood that certain features and sub-combinations are of utility and may be employed without reference to.other features and sub-combinations. This is contemplated by and is within thescope of my claims. Itis further obvious that various changes may be made in details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Havingx thus described my invention, what I claim is:

1.y In the digestion of cellulose bearing materials under heat and pressure in whichchemical is used for the digesting process, themethod of continuously extracting the chemical from the digested material 'including the steps of pressing the'hot digested material before the digesting pressure is`released, removing the chemical expressed from the compressed material, adding a fluid to the pressed material and again pressing the material to express a substantial portion of the iluid contained therein.

2. In a press of the character described, a tube having walls provided with strainer openings, a piston,'means for reciprocating said pis- 'ton' into said tube, a valve adapted to close the discharge end of said tube and means responsive to the density of the mass being pressed for controlling said valve. e

3. In a press of the character described, a tube provided with a discharge opening, means to force material through said tube, a valve for closing the dischargeopening of said tube, means in said tube responsive to the density ofthe material for operating said valve to close said tube discharge opening when the density of the material being forced through said tube falls below a predetermined value and to open said tube discharge opening when the density of the' material increases to a predetermined value.

4. In a device of the character described, a duct for conducting material to be compressed to a tube, a ram adapted to force the material to bev compressed through said tube, a sleeve valve adapted to control s aid duct and means for reciprocating said sleeve valve, and said ram in apredetermined timed. relation..

5. In a device of the character describeda sleeve valve, a tube having walls, a tubular valve seat for said valve spacedly positioned from the tube walls and forming a -tubular passageway therewith, said valve being adapted to, seat in said tubular passageway.

6. In the digestion of cellulose 4bearing material the method of continuously extracting lthe chemical therefrom, including the steps of pressing and diluting the hot digested material in successive stages before the digesting pressure is released.

7. A method of continuously separating fluid from a iluid containing material subjected to an elevated 'temperature and pressure substantially above atmospheric including the steps of pressing the material at substantially that elevated pressure and temperature lto a density sufficient to separate most of the fluid therefrom, adding fa diluting fluid to the material and again pressing the material to `a density sufficient to separate most of the fluid therefrom.

8. A method of continuously separating a chemically concentrated uid from a. fluid containing mass including the steps of pressing the mass to a density above 40% to separate most of the concentrated uid therefrom, adding a diluting fluid to the mass, again pressing the mass to a density above 40% to separate most of the diluted liquid therefrom and collecting the I liquids so4 separated. Y

9. A method of continuously separating. the fluid component from a heated fluid containing vmaterial including the steps of'pressing the material to a density above 40% and permitting fluid to separate therefrom, adding -a diluting fluid to the material in such quantity asto restore it to substantially its original fluid consistency, again pressing the material to a density above 40% and permitting fluid to separate therefrom. l

10. A method as defined by -claim 9 including the steps of comminuting the material following each of the pressing steps.

1l. A method of continuously separating the fluid component from a heated fluid containing material including the steps of pressing the material to `a density above'40% and permitting uid to separate therefrom, adding a hot diluting fluid to the material in such quantity as to restore it to substantially its original fluid consistency, again pressing the material to a density above 40% and permitting fluid to separate therefrom. l

12. A process comprising the steps of causing digested material containing digesting liquor to be substantially continuously transferred from a pressure digesting vessel into the sleeve of a pressing device through which digested material discharges from said vessel, mechanically compacting digested material in said sleeve into a dense internally unreinforced body forming a closure member for said sleeve not displaceable by the digesting vessel pressure and substan'v tially continuously compacting in said sleeve suclcessive increments of digested material against said closure member to express digesting liquor 

